1 © 2004, Cisco Systems, Inc. All rights reserved. CCNA 4 v3.1 Module 1 Scaling IP Addresses

222 © 2004, Cisco Systems, Inc. All rights reserved. Purpose of This PowerPoint This PowerPoint primarily consists of the Target Indicators (TIs) of this module in CCNA version 3.1. It was created to give instructors a PowerPoint to take and modify as their own. This PowerPoint is: NOT a study guide for the module final assessment. NOT a study guide for the CCNA certification exam. Please report any mistakes you find in this PowerPoint by using the Academy Connection Help link.

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444 © 2004, Cisco Systems, Inc. All rights reserved. Objectives

555 © 2004, Cisco Systems, Inc. All rights reserved. Private Addressing

666 © 2004, Cisco Systems, Inc. All rights reserved. NAT A NAT-enabled device typically operates at the border of a stub network.

777 © 2004, Cisco Systems, Inc. All rights reserved. NAT Terms Inside Local Addresses – An IP address assigned to a host inside a network. This address is likely to be a RFC 1918 private address. Inside Global Address – A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP address to the outside world. Outside Local Address - The IP address of an outside host as it known to the hosts in the inside network. Outside Global Address - The IP address assigned to a host on the outside network. The owner of the host assigns this address.

888 © 2004, Cisco Systems, Inc. All rights reserved. NAT Features Static NAT is designed to allow one-to-one mapping of local and global addresses. Outside DA Inside Internet Inside Global IP Address Inside Local IP Address NAT Table DA

999 © 2004, Cisco Systems, Inc. All rights reserved. NAT Features Dynamic NAT is designed to map a private IP address to a public address. Outside Inside Internet Inside Global IP Address Inside Local IP Address NAT Table SA SA

10 © 2004, Cisco Systems, Inc. All rights reserved. PAT Features PAT uses unique source port numbers on the inside global IP address to distinguish between translations. SA :2333 Outside Inside Internet SA :1456 SA : : : : :1456 Inside Global IP Address Inside Local IP Address NAT Table : :80 Outside Global IP Address Outside Local IP Address SA :

11 © 2004, Cisco Systems, Inc. All rights reserved. NAT Benefits Eliminates re-assigning each host a new IP address when changing to a new ISP Eliminates the need to re-address all hosts that require external access, saving time and money Conserves addresses through application port-level multiplexing Protects network security

12 © 2004, Cisco Systems, Inc. All rights reserved. Configuring Static NAT Translations Static translation are entered directly into the configuration and are permanent in the translation table Router(config)#ip nat inside source static

13 © 2004, Cisco Systems, Inc. All rights reserved. Inside/Outside interface An interface on the router can be defined as inside or outside Translations occur only from inside to outside interfaces or vice versa—never between the same type of interface NAT Inside Interface Inside Network Outside Network ip nat inside ip nat outside Inside Host Outside Host Router(config-if)#ip nat inside Outside Interface

14 © 2004, Cisco Systems, Inc. All rights reserved. Configuring Static NAT

15 © 2004, Cisco Systems, Inc. All rights reserved. Dynamic Translations Dynamic translation specify the pool of global addresses that inside addresses can be translated into Router(config)#ip nat pool nat-pool netmask Dynamic translations use access lists to identify IP addresses that NAT should create translations for Router(config)#ip nat inside source list 1 pool nat-pool Router(config)#access-list 1 permit

16 © 2004, Cisco Systems, Inc. All rights reserved. Configuring Dynamic NAT

17 © 2004, Cisco Systems, Inc. All rights reserved. Configuring PAT Establishes overload translation, specifying the IP address to be overloaded as that assigned to an outside interface Router(config)#ip nat inside source list 1 interface serial0/0 overload Establishes overload translation, specifying the IP address to be overloaded as that assigned to a pool name Router(config)# ip nat pool nat-pool netmask Router(config)#ip nat inside source list 1 pool nat-pool2 overload

18 © 2004, Cisco Systems, Inc. All rights reserved. Configuring PAT

19 © 2004, Cisco Systems, Inc. All rights reserved. Clearing the NAT Translation Table Clears all dynamic address translation entries Router#clear ip nat translation *

20 © 2004, Cisco Systems, Inc. All rights reserved. Verifying NAT and PAT Configuration

21 © 2004, Cisco Systems, Inc. All rights reserved. Troubleshooting NAT and PAT

22 © 2004, Cisco Systems, Inc. All rights reserved. Issues With NAT

23 © 2004, Cisco Systems, Inc. All rights reserved. DHCP DHCP works by providing a process for a server to allocate the IP information to clients.

24 © 2004, Cisco Systems, Inc. All rights reserved. Clients lease the information from the server for an administratively defined period. DHCP

25 © 2004, Cisco Systems, Inc. All rights reserved. BOOTP and DHCP Differences DHCP defines mechanisms through which clients can be assigned an IP address for a finite lease period. This lease period allows for re-assignment of the IP address to another client later, or for the client to get another assignment, if the client moves to another subnet. Clients may also renew leases and keep the same IP address. DHCP provides the mechanism for a client to gather other IP configuration parameters, such as WINS and domain name.

26 © 2004, Cisco Systems, Inc. All rights reserved. Major DHCP Features Automatic Allocation Manual Allocation Dynamic Allocation

27 © 2004, Cisco Systems, Inc. All rights reserved. DHCP Operation

28 © 2004, Cisco Systems, Inc. All rights reserved. The Order of DHCP Messages Transmitting

29 © 2004, Cisco Systems, Inc. All rights reserved. Configuring DHCP

30 © 2004, Cisco Systems, Inc. All rights reserved. Configuring DHCP While Excluding IP

31 © 2004, Cisco Systems, Inc. All rights reserved. Verifying DHCP

32 © 2004, Cisco Systems, Inc. All rights reserved. Troubleshooting DHCP

33 © 2004, Cisco Systems, Inc. All rights reserved. DHCP Relay

34 © 2004, Cisco Systems, Inc. All rights reserved. Summary